Apertures are important components of optical pickups and other optical apparatuses which, by limiting the optical path, eliminates stray light and other external disturbances.
FIG. 14 shows the conventional configuration of an optical head using an optical element proposed in, for example, Japanese Patent Application No. 2000-132897, Japanese Patent Application No. 2000-189730, or similar.
This optical element (lens element) 70 is configured by stacking a first lens substrate 73, in which a first objective lens 71 is embedded in a transparent substrate, and a second lens substrate 74, in which a second objective lens 72 is embedded in a transparent substrate.
The first and second objective lenses 71 and 72 have higher refractive indices than the respective surrounding transparent substrates.
By means of two lenses, which are the first objective lens 71 and the second object lens 72, the light beam L converges and irradiates the optical disc 80.
In the prior art, an aperture 75 to limit the optical path is, for example, formed from a collimating lens 76 or similar formed using conventional manufacturing methods, as shown in FIG. 14. In the configuration of FIG. 14, the aperture 75 comprises a lens holder of, for example, black plastic or similar, which holds the collimating lens 76.
However, for the configuration shown in FIG. 14, when for example axis inclination of the optical path occurs due to motion in the horizontal direction of the collimating lens 76, light may be guided into regions outside the effective area of the objective lenses 71 and 72, and the guiding of light into the region within the effective area may be prevented. As a result, stray light occurs, becoming light returning to the semiconductor laser or distorting the shape of the focused spot of laser light, and as a result generating noise or causing other problems.
In order to resolve the above problems, this invention provides an optical element and manufacturing method thereof which enables the avoidance of stray light and noise, by preventing the incidence of light on unnecessary portions and by ensuring that light is not prevented from being guided to the region within the effective area.